1. Field of the Invention
The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus having a charge removal device to remove a residual potential on the surface of a photosensitive body.
2. Description of the Related Art
An image forming apparatus is an apparatus which prints an image on a printing medium, e.g., paper, according to an inputted image signal. Of the various types of image forming apparatuses, an electro-photographic image forming apparatus typically prints an image on paper through paper feeding, developing, transfer, fusing and paper discharge processes. In order to perform the developing process to develop an electrostatic latent image into a visible image on a photosensitive body, an image forming apparatus generally includes a charge roller, a laser scanning device, a developing roller, a cleaning device and a charge removal device.
The photosensitive body is charged to a predetermined electric potential by the charge roller, and the laser scanning device scans light on so charged surface of the photosensitive body charged to form an electrostatic latent image. The developing roller supplies toner to the electrostatic latent image to develop the electrostatic latent image into a toner image, and the toner image thus developed is transferred onto paper. Some residual toner may remain on the photosensitive body after the toner image is transferred onto paper. Such residual toner is removed by the cleaning device.
The charge removal device removes the residual potential remaining on the photosensitive body surface by irradiating light on the photosensitive body, e.g., prior to the next printing process. For example, FIG. 1 schematically illustrates a conventional charge removal device, which may include a plurality of light emitting diode (LED) lamps 2 which are arranged in one or more rows across the longitudinal direction of the photosensitive body 1, each of the LED Lamps facing the latent image forming surface of the photosensitive body.
The above described arrangement of LED lamps 2 may be advantageous in irradiating light evenly on the photosensitive body 1, unfortunately, it may also, however, result in higher cost, and larger size, of the image forming apparatus.
Reductions in the number of LED lamps in an attempt to save cost may result in gaps in the coverage of light between the LED lamps, and thus may adversely effect the uniformity in the light irradiated on the various regions of the photosensitive body surface, which may cause deterioration of the image quality and/or printing defects.
An optical charge removal device disclosed in the US Patent Application Publication No. U.S. 2006/0060751 to Nishimura et al. (“Nishimura”) includes a light guide member, which is mounted in parallel with the length of the photosensitive body. The light guide member includes a reflective surface, on which the light emitted from an LED lamp is incident, and which reflects the light onto the surface of the photosensitive body. According to Nishimura, by adequately designing the shape of the reflective surface of the light guide member, it is possible to evenly irradiate light in the axial direction of the photosensitive body.
Unfortunately, however, even in those charge removal devices suggested by Nishimura and others still require a complicated light path from the source of the light, e.g., an LED lamp, to the light guiding member, and in turn reflective path to the photosensitive body. To provide such reflective light path, the device of Nishimura also requires complex light guide member structure and/or the structure of the reflective surface thereof, which in-and-of-itself presents a technical challenge, and which may also contribute to increase in the component costs and/or the size of the image forming apparatus.
In addition, because a mounting space of the light guide member should be provided in the vicinity of the photosensitive body, where many other components for development may already be densely populated, the charge removal device of Nishimura and the likes may cause difficulties in the design and assembly of the image forming apparatus.